1. Field of the Invention
The present invention relates to a valve actuating apparatus for intake and exhaust valves in an internal combustion engine. More particularly, it relates to a valve actuating apparatus which can render only a predetermined intake and/or exhaust valve or valves inoperative at a given engine condition.
2. Description of the Related Art
In a multi-cylinder internal combustion engine, it is known to selectively render only predetermined intake or exhaust valve(s) inoperative in order to cancel out the associated cylinder(s), thereby controlling the total displacement of the effective cylinders, in accordance with the engine load, resulting in the realization of a variable-cylinder internal combustion engine.
Among known valve actuating apparatuses of the kind mentioned above, those closest to the present invention are disclosed, for example, in Japanese Unexamined Utility Model Publication (Kokai) Nos. 59-68109 and 59-67506, in which a rocker arm is divided into two rocker arm elements, one of which bears against a cam and the other bears against a valve stem of the associated intake or exhaust valve. These two arms are interconnected for relative sliding rotation. The relative sliding rotation takes place between the two arms when only a predetermined intake or exhaust valve is made temporarily inoperative, to absorb the valve lift of the associated valve. The two arms are provided with male and female engaging members which are selectively engaged and disengaged. One of the male and female members can be actuated by an actuator, such as solenoid means to selectively occupy locked and unlocked positions.
However, in the known apparatuses mentioned above, the actuator acts on the male or female member in a direction parallel to the axis of the rocker arm shaft on which the rocker arm is supported, namely in a direction in which the two arm elements tend to separate and, accordingly, the two arm elements originally brought into surface contact are forced to separate from one another. This results in deviation of the arm elements from the respective initial positions or undesirable displacement of the contact portion of the second arm element that bears against the valve stem.